Preheat oven to 350. Grease and flour two 9" round baking pans. Whisk together the flour, sugar, baking soda, and salt in a large bowl. In a large measuring cup, combine the oil, vanilla, and water. Add wet ingredients to dry ingredients and stir until well blended. Add vinegar and quickly stir until thoroughly incorporated. Pour batter into prepared pans. Bake for 35-45 minutes or until toothpick comes out clean. Cool in pans for 10 minutes and the invert to cool completely. Frost with buttercream frosting if desired.